1. Field of the Invention
The present invention relates to thermally insulating pistons for internal combustion engines, and to a method of producing such thermally insulating pistons.
The worldwide increased costs of fuels utilized for internal combustion engines has led to intensive efforts in obtaining improved fuel savings or economy. One of the possibilities in obtaining fuel savings through thermally insulating the combustion chamber, in effect, the cylinder walls, the cylinder head;, and especially, however, the piston crown, through which there escapes a substantial portion of the heat.
2. Discussion of the Prior Art
There are presently known some ceramic materials possessing a thermal conductivity .lambda. of less than 2 or 3 W/m .degree.K, which would render them ideal as insulators for piston crowns; nevertheless, such piston crowns or the dished combustion chamber portions of the pistons which are insulated with these ceramic material have hitherto remained unknown. The reason for this is attributed to the difficulties connected in the depositing of ceramic materials on the metallic piston. Thus, heretofore been impossible to form a bound between ceramic components and the piston material; for instance, Silumin (cast aluminum alloy with 10 to 25% Si) preferred for this purpose, which possesses the necessary mechanical strength under the temperatures or temperature differences reigning in the internal combustion engine.